Digging tip



Aug. 21, 1962 G. w. MCININCH DIGGING TIP Filed April 21, 1961 2 Sheets-Sheet 1 INVENTOR. GLENN W. MC ININCH BYW,W-M/QM A'rTYs,

Aug. 21, 1962 w. MCININCH 3,049,824

DIGGING TIP Filed April 21, 1961 2 Sheets-Sheet 2 WIDTH OF TRENCH Ar-rvs.

3,049,824 DIGGING TIP Glenn W. Mclninch, Omaha, Nehru, assignor to Auburn Machine Works, Inc, Auburn, Nehru, a corporation of Nebraska Filed Apr. 21, 1961, Ser. No. 104,615 4 Claims. (Cl. 31-191) The present invention relates to improvements in trench digging machines and more particularly to detachable digging tips which may be replaced when worn or damaged.

It is an object of the present invention to provide an improved digging tip for trenching machines and the like which is easy to install, dependable in operation and inexpensive to manufacture and replace since the tip may be removed and replaced independently of its supporting shank.

More specifically, it is an object to provide a digging tip wherein the materials of the tip may be tailored to provide a specific wear resistance during digging with the supporting shank being formed of a dilferent material.

It is also an object to provide a digging tip which cannot be dislodged during normal digging, but rather, tends to seat more firmly on the supporting shank due to the novel design. A more particular object is to pro vide such a digging tip wherein a corner of the attaching socket may be peened over into a cooperating recess of the supporting shank to prevent dislodgment, but nevertheless, allowing the tip to be easily removed by simply hammering on its rear portion causing the peened over area to yield.

An additional object is to provide a digging tip which due to its novel construction may be installed upon a supporting shank with the blade of the tip selectively oriented in one of several cutting planes with respect to the forward movement of the digging chain.

A further object is to provide a supporting shank for a tip of the above type which may be attached to the digging chain of a trenching machine or the like in one of a plurality of lateral positions thereby adjusting the cutting width of the chain.

Other objects and advantages of the invention will become apparent from reading the attached detailed description and upon reference to the drawings in which:

FIGURE 1 is an exploded side elevation of the novel digging tip and its associated supporting shank attached to the digging chain of a trenching machine;

FIG. 2 is an exploded rear elevation of the shank holder and support shank;

FIG. 3 is a plan view of the digging tip;

FIG. 4 is a sectional view taken along the line 4-4 in FIG. 1;

FIG. 5 is a plan view of the shank holder;

FIG. 6 is a plan view of the support shank;

FIG. 7 is a simplified diagrammatic view showing the lateral orientation of the digging tips;

FIG. 8 is a simplified diagrammatic view showing the normal angular orientation of the digging tips; and

FIG. 9 is similar to FIG. 8 showing an alternative angular orientation of the digging tips.

While the invention will be described in connection with a preferred embodiment, it will be understood that I do not intend to limit the invention to that embodiment, but on the contrary, I intend to cover alterations, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Turning to the drawings, there is shown in FIG. 1 a digging assembly incorporating the features of the present invention. In the preferred embodiment, this dig- 3,049,824 Patented Aug. 21, 1962 ging assembly comprises a removable tip 11 and a supporting shank 12 mounted on a holder 13. The holder 13 is shown attached to a portion of an endless digging chain 14- of the type commonly employed in trenching machines. Reference may be had to my earlier Patent No. 2,666,273 issued January 19, 1954, for the details of such a digging chain. Sufiice it to say that the chain 14 is comprised of a series of outside links 15 overlapping and connected to the alternating inside links 16 by means such as pins 17 passing through matching holes in each end of the links and securing rollers 18 between the chain links.

In spaced sequence the holders 13 are attached to the digging chain 14 to provide for mounting the novel supporting shanks 12 and digging tips 11. The holders have a body portion or saddle 19 which overlies the chain, and a pair of mounting legs 20 which project downwardly from the saddle 12 along the sides of the chain. The legs 20 are spaced apart a distance equal to the spacing between a pair of outside links 15 so that a pair of outside chain links may be readily replaced by the legs 20 of the holders. The holders are connected to the chain and held in straddling position by transverse pins 17 passing through holes in the legs spaced to correspond to the holes in the pairs of outside links 15 replaced by the holders.

Additional support for the digger-bit holders is provided by rearwardly extending lugs or projections 21 formed integrally with the upper edge portion of the legs 20 of the holder. The lugs 21 project rearwardly to or slightly beyond the axis of the next adjacent pin 17 of the chain and have their bottom edges curved upwardly to conform to the contour of the following outside links 15. It will be apparent by reference to FIG. 1 that the lugs 21 resist rearward tipping forces on the holder and provide a third point of support greatly increasing the strength and evenness of operation of the digger chain.

In accordance with the present invention the supporting shanks 12 are mounted on the holders 13 and carry the novel detachable digging tips 11 at their forward ends. Since the shanks 12 and tips 11 are of uniform construction, only one of each need be described here in detail. The shank 12 has an enlarged base portion 22 for attachment of the shank to the saddle 19 of the holder 13 by means such as welding. Projecting downwardly from the base 22 a locating lug 23 is formed integrally with the base for insertion into a cooperating opening 24 in the saddle 19. The body 25 of the shank is inclined upwardly from the base 22 at an angle of about 20 which has been found to provide adequate clearance for the digging tip and a desirable orientation with respect to the movement of the digging chain. In the preferred embodiment, the nose or coupling end 26 of the shank is formed with a pentagonal cross-section, with each of the five sides 27 converging at the forward end to provide a pyramidical shaped nose. The sides 27 of the pyramidical nose 26 terminate at their rearward end with a step or shoulder 28 which merges into the body 25 of the support shank 12.

Mounted on the nose of the shank 12 is a replaceable digging tip 11. As shown in FIGS. 1 and 3, the digging tip comprises a flat substantially rectangular blade 29 with a pentagonal shank receiving socket 30 integrally molded thereon. The blade 29 has flat upper surface 31 and a bevelled lower surface 32, tapered at their forward ends to form a cutting or working edge 33. The lower or working surface 32 and the cutting edge 33 being subjected to severe abrasive action in the digging operation may be induction hardened to provide for greater wear resistance and thus longer life.

The pentagonal shank receiving socket 30 has four uniformly converging walls 34, which together with a fifth side formed by an enclosed portion of the upper surface 31 of the blade merge together to form a pyramidical enclosure. The socket 30 is designed for mating engagement on the nose 26 of the support shank 12 which con forms to the pyramidical construction of the socket 39. It may be seen that as the working edge 33 of the blade 29 bites into the ground during the digging operation, the resulting force tends to urge the socket into more binding engagement with the nose of the shank due to the pyramidical construction of the mating surfaces.

It is also a feature of the present invention that the digging tip 11 is locked into place on its cooperating sup port shank merely by deforming a corner 35 of the socket 30 so that it locks over an associated shoulder 28 of the support shank 12. This may, of course, be done in any suitable manner as for example, by peening over the cor ner 35 with a hammer. Thus, not only does the digging tip become more securely attached during normal digging, but also, the locking achieved by peening over the corner 35 prevents the tip from being dislodged if the trenching chain is reversed. Nevertheless, the tip can easily be removed from the supporting shank simply by hammering on the base 36 of the blade 2? causing the corner 35 to yield and return to its former and substantially unde formed shape.

For digging a trench of greater width than that of an individual digger-bit, the holders 13 are adapted to provide increasing lateral offset of the tips 11. To accom plish this, the holders 13 are formed into right and left hand pairs merely by locating the opening 24 respectively right or left of the centerline. (See FIG. 5.) In the illustrated embodiment two alternating pairs of holders are employed with the opening 24 farther off-center in one pair than in the other. Thus, when the shank 12 is mounted on the holder 13, the lug 23 is inserted into the opening 24 and the base 22 is then welded to the saddle 19 at the desired orientation to provide lateral off-setting of the tip from the chain. It is desirable that the lateral positioning of the tips 11 is such that slight overlap occurs in their sequential cutting and digging movement. (See FIG. 7.) Of course it would also be possible to provide one holder in the sequence with a saddle having an opening on its centerline and one or more pairs of right and left oriented holders without departing from the scope of the present invention. It may also be seen that the width of the trench which is dug is defined by the distance between the outside corners of the widest off-set tips.

By providing the socket 30 with the illustrated pentagonal pyramidical design it is also possible to mount the tip 11 on the supporting shank 12 in a plurality of angular orientations. As shown in FIG. 8, the digger-tips are mounted on the support shanks for normal digging operation of normal packed earth or loam. In this position the cutting edge 33 of the tip is substantially parallel to the transverse plane of the endless chain 14'. Positive interference between the flat sides of the pentagonal cross sections of the nose 26 and the socket 3% holds the bit in the desired angular position. It will be apparent, however, that the tip may be mounted on the shank with the blade '29 inclined at various angles with respect to the normal position by orienting the bit through the angle required to bring succeeding sides of the socket into parallel with the sides of the nose.

I have found that the digging of sandy, loosely packed soil is greatly improved by turning the working face 32 of the tip inwardly toward the center of the shank 12 as shown diagrammatically in FIG. 9. Hard, stony soils and clay, on the other hand are effectively dug by o rienting the digger tips in the opposite direction. In the pre ferred embodiment, the nose 2.6 of the shank is pentagonal in cross-section, as above described, and permits the blade 29 of the tip to be turned through an angle of about 72 to either side of the normal cross-wise blade position. In short, the angularity obtained by using the pentagonal nose and socket permits highly effective working areas and angular relationships to be obtained for different types of soils with but a single shank and socket construction.

It is further apparent that the onerpiece construction of the di ging tip enables it to be easily and economically manufactured. The entire tip may be forged or cast in a single piece or made of a welded construction, and the working surface and cutting edge uniformly induction hardened to produce a hardness approximately on the Rockwell C Scale. This hardness has been found to be sufficient to give good wearability under normal digging conditions but, nevertheless, the unit is soft enough so that the tip does not break on striking a rock or the like. Since only the working portion of the tip need be hardened, this also makes it possible to peen over a corner of the socket for locking purposes without cracking the metal. The above hardness is, however, merely illustrative and for special digging conditions, different heat treatment may be desirable.

Additional savings are accomplished by making it unnecessary to replace the entire supporting shank when the tip 11 becomes dull or worn through use. Also the shank may be made of a different material and hardness than the tip, thus, saving on material costs. Each part, therefore wears longer because the hardness can be closely tailored to the function which the part is to perform.

I claim as my invention.

1. For use in a trenching machine having an endless loop of roller chain, the chain having alternating pairs of overlapping inside and outside links, the combination comprising, a supporting shank having a base portion and a nose portion of pyramidal shape, said base having a positioning lug projecting therefrom, a digging tip having a blade and a shell defining a pyramidal socket molded thereto, said socket being dimensioned to mate intimately surface to surface with the nose portion of the shank, a base plate secured to a pair of links on the roller chain, said base plate having a locating hole therein for insertion of said positioning lug to locate said shank and digging tip with respect to the chain.

2. For use in a trenching machine having an endless loop of roller chain, the chain having alternating pairs of overlapping inside and outside links, the combination comprising, a supporting shank having a base portion and a polygonal nose portion extending therefrom, a positioning lug projecting from said base, a bit having a blade and a shell defining a polygonal socket molded thereto, said polygonal socket being adapted for coupling associa-tion with said polygonal nose in a selected one of a plurality of predetermined angular positions relative to said shank, a holder for said shank having a saddle portion and downwardly projecting legs, said legs having spaced holes therein arranged for connecting said holder to the chain in place of a pair of outside links of the latter, said legs having rearwardly extending projections adjacent their upper ends shaped to bear against the upper edge of the next following outside links of the chain, said holder also having a locating opening in said saddle for insertion of said positioning lug of said shank for locating the shank and digging tip with respect to the chain.

3. For use in a trenching machine having an endless loop of roller chain with alternating pairs of overlapping inside and outside links, the combination, comprising, a base plate carried by a pair of outside links on the roller chain, a shank having a cylindrical body portion and a pyramidal nose portion carried by said base plate, said pyramidal nose portion being pentagonal in cross section and terminated by an annular shoulder adjacent said body portion, said shoulder defining a step projecting radially outwardly from said cylindrical body portion, a digging tip having integral blade and shell portions with the shell defining a pyramidal socket on one side of the blade, said socket being dimensioned to mate intimately surface-tosurface with said nose portion and to overlie said shoulder thereby permitting any portion of the overlying socket to be deformed against any portion of said step to lock said tip on said shank, and said shank projecting from said base plate and being oriented with respect to the center line of the roller chain so as to sweep said blade through a fixed path parallel to the movement of the roller chain.

4. For use in a trenching machine having an endless loop of roller chain with alternating pairs of overlapping inside and outside links, the combination, comprising, a base plate carried by a pair of outside links on the roller chain, a shank having a cylindrical body portion and a pyramidal nose portion carried by said base plate, said pyramidal nose portion being pentagonal in cross section and terminated by an annular shoulder adjacent said body portion, said shoulder defining a step projecting radially outwardly from said cylindrical body portion, a digging tip having integral blade and shell portions with the shell defining a pyramidal socket on one side of the blade, said socket being dimensioned to mate intimately surface-tosurface with said nose and to overlie said shoulder thereby permitting any portion of the overlying socket to be deformed against any portion of said step to lock said tip on said shank, and said shank having a longitudinally inclined axis oriented to intersect a transverse plane through said base plate and to define an outwardly extending angular position of said nose portion with respect to said base plate so as to carry said blade in an ofiset divergent relationship to the roller chain thereby defining the relative bite and angle of attack of said digging tip.

References Cited in the file of this patent UNITED STATES PATENTS 836,856 Bourque Nov. 27, 1906 1,262,870 Thomson Apr. 16, 1918 1,333,852 Kittredge Mar. 16, 1920 1,909,850 Younie May 16, 1933 1,978,733 Yocum Oct. 30, 1934 2,666,273 McIninch Jan. 19, 1954 2,870,552 Richardson Jan. 27, 1959 2,885,801 Hill May 12, 1959 2,915,290 Petersen Dec. 1, 1959 

